Ruthenium-Catalyzed Reductive Amidation without an External Hydrogen Source

A catalytic reaction between aldehydes and primary amides that leads to N-alkylated amides was investigated. The developed protocol employs carbon monoxide as a deoxygenative agent and, therefore, avoids the use of an external hydrogen source. Cyclopentadienyl ruthenium complexes provided excellent catalytic efficiency and could be used with loadings as low as 0.5-1 mol-%. A representative number of secondary amides were successfully prepared in yields of 70-84%.